Pattern Syntax

This chapter contains focuses on the pattern syntax for regular expressions. It starts with an overview and details for each pattern element.

• Syntax Overview
  • Quoting
  • Special Characters
  • Character Types
  • Character Classes
  • Quantifiers
  • Anchors
  • Alternatives
  • Groups
  • Modes and Flags
  • Unsupported Expressions
• Quoting
  • Strict Escaping
  • Literal Quoting Escapes
  • Quoting Inside Character Classes
  • Legacy and Compatibility Expressions
• Special Characters
  • Line Feed: \n
  • Carriage Return: \r
  • Horizontal Tab: \t
  • Four-Digit Unicode Escape: \uhhhh
  • Variable-Length Unicode Escape: \u{hh…}
  • Legacy and Compatibility Expressions
• Character Types
  • Any Character: .
  • Digit: \d
  • Non-Digit: \D
  • Whitespace: \s
  • Non-Whitespace: \S
  • Word Character: \w
  • Non-Word Character: \W
  • Unicode General Category: \p{category}
  • Negated Unicode General Category: \P{category}
  • Supported Unicode Categories
  • Legacy and Compatibility Expressions
  • Differences from Common Regex Engines
• Character Classes
  • Character Class: […]
  • Negated Character Class: [^…]
  • Legacy and Compatibility Features
  • Differences from Common Regex Engines
• Quantifiers
  • Quantifier Flavors
  • Quantifier Overview
  • Optional Quantifiers
  • Repetition Quantifiers
  • One-or-More Quantifiers
  • Counted Quantifiers
  • Open-Ended Counted Quantifiers
  • Possessive Quantifiers
  • Counted Quantifier Limits
  • Legacy and Compatibility Quantifiers
  • Differences from Common Regex Engines
• Anchors
  • Start of Input: \A
  • Word Boundary: \b
  • Non-Word Boundary: \B
  • End of Input: \Z
  • Start of Input or Line: ^
  • End of Input or Line: $
  • Legacy and Compatibility Anchors
  • Notes and Compatibility
• Alternatives
  • Alternation: A|B|C
  • Grouped Alternation: (?:A|B|C)
  • Empty alternatives and empty groups
• Groups
  • Capturing Group: (…)
  • Named Capturing Group: (?<name>…)
  • Non-Capturing Group: (?:…)
  • Atomic Group: (?>…)
  • Legacy and Compatibility Syntax
  • Differences from Common Regex Engines
• Modes and Flags
  • Standard Flags
  • Inline Flag Sets
  • Local Flag Overrides
  • Unsupported Standalone Flag Removal
  • Legacy and Compatibility Flags
  • Differences from Other Regex Engines
• Unsupported Expressions
  • Numeric and Ambiguous Escapes
  • Byte-Oriented and Line-Oriented Escapes
  • Unicode and Text Segmentation
  • Backtracking-Dependent Constructs
  • Control-Flow and State-Based Syntax
  • Parser and Engine Directives
  • Conditional Patterns
  • Empty Groups and Alternatives
  • Summary